PTERIDoIMIYTKS 



J 53 



cross section of fer- 

 tile spike, showing 

 the two sporoge- 

 nous bands at 



modium that grows among the blocks of sporogenous cells and ramifies 

 into every intercellular space (fig. 360). 



Gametophyte. — The gametophyte is of the Lycopodium type. In 

 Ophioglossum, which is regarded as the most primitive genus, the game- 

 tophyte is a tuberous, subterranean body that gives 

 rise to aerial green lobes that bear the sex organs. 

 In Botrychium there is no aerial portion, the game- 

 tophyte being completely subterranean and tuberous 

 (fig. 361). In Hclminthostachys the gametophyte is 

 somewhat intermediate in structure, the tuberous body 

 giving rise to a cylindrical aerial process that bears 

 the sex organs. In every case the tuberous body rangiaof Ophioglos- 

 contains an endophytic fungus, as in the gametophyte sum: diagrammatic 

 of Lycopodium. It is evident that the gametophyte 

 of the Ophioglossales suggests that of the Lyco- 

 podiales; but that the 

 sporophyte is more like ZTLlT~ 

 that of Filicales. 



Sex organs. — The antheridia develop 

 as usual among the eusporangiates, the 

 inner cell, following the periclinal division 

 of the superficial initial, giving rise to the 

 spermatogenous tissue. The sperms are 

 large, coiled, and multiciliate, a type not 

 found among the Lycopodiales, but char- 

 acteristic of the Filicales. 



The archegonium of Ophioglossum has 

 a very short neck, the neck canal cells 

 being only two in number, the same 

 reduced number as in Equisetum. In 

 Botrychium (figs. 362-365) the neck of the 

 archegonium is long, but contains only 

 four neck canal cells. 



Embryo. — In general there is no sus- 

 pensor, but in the recently described genus 

 Sceptridium a massive suspensor is re- 

 ported, at least for one species (formerly 

 Botrychium obUquiim). There is no differentiation of the great body 

 regions at the quadrant stage, but in Botrychium, for example, there is 



Fig. 360. — Portion of a nearly 

 mature sporangium of Ophio- 

 glossum, showing the tapetal 

 Plasmodium (with nuclei) among 

 the groups of mother cells. — 

 After Bower. 



